Compositions of polyphenylene oxides and alkenyl aromatic resins are known in the art. The polyphenylene oxides are disclosed in Hay, U.S. Pat. No. 3,306,874 and U.S. Pat. No. 3,306,875, and in Stamatoff, U.S. Pat. Nos. 3,257,357 and 3,357,358. In the Hay patents, the polyphenylene oxides are prepared by an oxidative coupling reaction comprising passing an oxygen-containing gas through a reaction solution of a phenol and a metal-amine complex catalyst. Other disclosures relating to processes for preparing polyphenylene oxide resins, including graft copolymers of polyphenylene oxide resins with styrene type compounds, are found in Fox, U.S. Pat. No. 3,356,761; Sumitomo, U.K. Pat. No. 1,291,609; Bussink et al U.S. Pat. No. 3,337,499; Blanchard et al, U.S. Pat. No. 3,219,626; Laakso et al, U.S. Pat. No. 3,342,892; Borman, U.S. Pat. No. 3,344,166; Hori eta al, U.S. Pat. No. 3,384,619; Faurote et al, U.S. Pat. No. 3,440,217; Olander, U.S. Pat. No. 3,956,242; and disclosures relating to metal based catalysts which do not include amines, are known from patents such as Wieden et al, U.S. Pat. No. 3,442,885 (copper-amidines); Nakashio et al, U.S. Pat. No. 3,573,257 (metal-alcoholate or -phenolate); Kobayashi et al, U.S. Pat. No. 3,455,880 (cobalt chelates); and the like. In the Stamatoff patents, the polyphenylene ethers are produced by reacting the corresponding phenolate ion with an initiator, such as a peroxy acid salt, an acid peroxide, a hypohalite, and the like, in the presence of a complexing agent. Disclosures relating to non-catalytic processes, such as oxidation with lead dioxide, silver oxide, etc., are described in Price et al, U.S. Pat. No. 3,382,212. Cizek, U.S. Pat. No. 3,383,435 discloses polyphenylene oxide resin compositions. All of the above-mentioned disclosures are incorporated by reference.
Alkenyl aromatic resins have been prepared by polymerizing an appropriate alkenyl aromatic monomer in the presence of a polyphenylene oxide resin. Disclosures of such processes are found in Tabana et al, U.S. Pat. No. 3,751,388; Erchak et al, U.S. Pat. No. 3,384,682; Erchak et al, U.S. Pat. No. 3,487,127; Yamanouchi et al, 3,700,650; and Nakanishi et al, U.S. Pat. No. 3,664,977. It has been found that impurites in polyphenylene oxide resins, such as catalyst residues have had an adverse effect on the polymerization rates of alkenyl aromatic monomers such as styrene, when these monomers have been polymerized in the presence of polyphenylene oxide resins. The applicant has discovered that the speed of polymerization and/or the ultimate molecular weight of the alkenyl aromatic resin may be raised by the addition to the polymerization reaction of alumina, a monobasic acid anhydride, water or a mixture of water and alumina.
Accordingly, it is a primary object of the present invention to provide an improved process for the polymerization of alkenyl aromatic monomers in the presence of a polyphenylene oxide resin.